The interwar period was marked by a mix of political ideologies, rising nationalism, economic instability, and the failure of international diplomacy, which set the stage for World War II. In particular, fascism, extreme nationalism, and racial ideologies gained traction, while Western democracies, weakened by the aftermath of WWI, struggled to contain these forces.
The failure of the League of Nations, which had been established to prevent further conflicts after World War I, is a critical factor in understanding the political climate of the time. The League’s inability to enforce its resolutions, combined with American isolationism, meant that aggressive actions by fascist states went largely unchecked. Additionally, the distrust between Western democratic powers and the communist Soviet Union played a role in the global dynamics that allowed fascist powers to expand unchecked.
Failure of the League of Nations and Global Isolationism
U.S. Isolationism and Lack of Global Leadership
After World War I, the United States adopted an isolationist stance, focusing on domestic issues rather than European affairs. The U.S. refused to join the League of Nations, leaving the organization without the authority or support it needed to intervene in international conflicts. This created a power vacuum and allowed fascist regimes to rearm and expand their territories.
- U.S. Isolationism: The U.S. chose to avoid entanglement in European political and military matters, partly due to disillusionment over the aftermath of WWI. This lack of involvement contributed to the failure of collective security measures and emboldened fascist regimes like Nazi Germany and Fascist Italy.
States' Expansion Allowed by European Powers
The table below outlines some key examples of how fascist states violated post-WWI agreements and expanded their territories with little intervention from the Western democracies, further destabilizing Europe.
| Violation | Details |
|---|---|
| Germany Remilitarizes the Rhineland (1936) | Germany sent troops into the Rhineland, an area that had been demilitarized according to the Treaty of Versailles. This bold move was a direct challenge to France and the European powers, but France did not intervene, fearing another war. Hitler’s reoccupation of the Rhineland helped pave the way for further territorial expansion. |
| Italy Invades Ethiopia (1935) | Mussolini's invasion of Ethiopia was an attempt to expand Italian colonial holdings. Despite opposition from Britain and France, the League of Nations failed to take significant action to prevent the invasion. Italy's success further showcased the League's impotence. |
| Anschluss of Austria (1938) | Germany annexed Austria in March 1938, violating the Treaty of Versailles and the Treaty of St. Germain. The annexation was largely welcomed by the Austrian public and the fascist government. Despite some protests, no significant resistance came from other European powers, further demonstrating the failure of diplomatic efforts. |
| Appeasement of Hitler and the German Annexation of the Sudetenland (1938) | At the Munich Conference, Britain and France agreed to allow Germany to annex the Sudetenland, part of Czechoslovakia, in exchange for promises of no further territorial expansion. This appeasement policy, led by British Prime Minister Neville Chamberlain, is often cited as a key factor in emboldening Hitler and laying the groundwork for WWII. |
| Nazi-Soviet Non-Aggression Pact (1939) | The Molotov-Ribbentrop Pact between Nazi Germany and the Soviet Union guaranteed that both nations would refrain from attacking each other. It also secretly divided Eastern Europe into spheres of influence, including the partition of Poland, violating the Treaty of Versailles and setting the stage for WWII. |
Fascism and Nationalism: Rising Political Movements
Fascist and Authoritarian Ideologies
The interwar period saw the rise of fascist and totalitarian regimes, particularly in Italy, Germany, and Spain. Fascist movements capitalized on the economic instability, national humiliation from WWI, and fear of communism to gain mass support. These movements promoted aggressive nationalism, militarization, and the glorification of war.
- Fascism: Characterized by authoritarian rule, the suppression of political dissent, extreme nationalism, and the use of violence and propaganda to maintain control, fascism became a major force in Europe during the 1920s and 1930s.
- Nationalism: In countries like Germany and Italy, fascist leaders used nationalism to justify territorial expansion and the restoration of national pride. This included the promotion of ethnic superiority, particularly the idea of "Aryan" racial purity in Germany.
Rise of Fascist Leaders
- Benito Mussolini (Italy): Mussolini rose to power in Italy after the economic turmoil and political instability following WWI. In 1922, he became Prime Minister and later established a totalitarian regime. Mussolini's Fascist Party was marked by aggressive nationalism and militarism.
- Adolf Hitler (Germany): Hitler took advantage of economic hardship, political instability, and nationalist resentment in post-WWI Germany to build a popular fascist movement. By 1933, Hitler had become Chancellor, and by 1934, he had consolidated his power, becoming the Führer of Nazi Germany.
- Francisco Franco (Spain): Franco led a fascist uprising in the Spanish Civil War (1936–1939), with the support of Italy and Germany. After defeating the Republicans, Franco ruled Spain as a dictator until his death in 1975.
The Failures of Appeasement and the Path to War
The policies of appeasement followed by Britain and France in the 1930s failed to contain the ambitions of fascist regimes. In an effort to avoid another war, both countries made significant concessions to Nazi Germany, allowing it to rearm and expand its territory. These concessions were intended to keep peace but instead emboldened Hitler and increased tensions across Europe.
- The Munich Agreement (1938): The agreement, which allowed Germany to annex the Sudetenland, is often seen as a failure of diplomacy. By permitting Hitler to expand his territory without facing military opposition, Britain and France unintentionally paved the way for further aggression and war.
Consequences of the Failure of Diplomacy
- The Start of WWII: The failure of the League of Nations, the unchecked expansion of fascist states, and the ineffective policies of appeasement ultimately led to the outbreak of World War II. Germany’s invasion of Poland in September 1939 prompted Britain and France to declare war, marking the beginning of the conflict.
- The Spread of Totalitarianism: The interwar period saw the consolidation of totalitarian regimes in several European countries, fundamentally altering the political landscape of the continent. The rise of these regimes—rooted in fascism, nationalism, and racial ideologies—posed a direct challenge to the values of democracy and human rights.
Conclusion
The interwar period was a time of instability, political experimentation, and the failure of diplomacy. The economic turmoil of the 1920s and 1930s, the rise of fascism, and the inability of Western democracies to effectively confront these threats created a volatile environment that ultimately led to the outbreak of World War II. The appeasement of fascist powers, the rise of nationalism, and the breakdown of international institutions all contributed to one of the most catastrophic conflicts in European history.
Vocabulary
The following words are mentioned explicitly in the College Board Course and Exam Description for this topic.
| Term | Definition |
|---|---|
| American isolationism | The United States policy of avoiding political and military involvement in European affairs during the interwar period. |
| Annexation of Austria | Nazi Germany's 1938 incorporation of Austria into the Third Reich, violating the Treaty of Versailles. |
| Appeasement | A diplomatic policy of making concessions to an aggressive power to avoid conflict, notably pursued toward Nazi Germany in the 1930s. |
| Extreme nationalism | An intense form of national pride and loyalty that prioritizes the nation above all other considerations, often leading to aggressive foreign policy. |
| Fascism | An authoritarian political ideology that emerged in the early 20th century, characterized by extreme nationalism, rejection of democracy, centralized autocratic government, and often the glorification of war and a charismatic leader. |
| fascist states | Totalitarian nations governed by fascist ideology, including Nazi Germany, Fascist Italy, and Imperial Japan during the interwar and World War II periods. |
| Italian invasion of Ethiopia | Italy's 1935 military conquest of Ethiopia, demonstrating fascist expansion and the League of Nations' inability to stop aggression. |
| Munich Agreement | The 1938 agreement between Britain, France, Germany, and Italy that allowed Nazi Germany to annex the Sudetenland from Czechoslovakia. |
| Nazi-Soviet Non-Aggression Pact | The 1939 agreement between Nazi Germany and the Soviet Union pledging mutual non-aggression and secretly dividing Eastern Europe into spheres of influence. |
| Racist ideologies | Systems of belief asserting the superiority or inferiority of certain racial groups, used to justify discrimination and violence. |
| Remilitarization of the Rhineland | Nazi Germany's 1936 military reoccupation of the Rhineland, a demilitarized zone established by the Treaty of Versailles. |
Frequently Asked Questions
What is the interwar period and why is it important?
The interwar period is the years between WWI and WWII (roughly 1919–1939). It’s important because it shows how political and ideological shifts—economic collapse, widespread fear of another war, American isolationism, and deep distrust between democracies and the Soviet Union—enabled fascist, authoritarian, and racist movements to grow and expand. Key examples: remilitarization of the Rhineland, Italian invasion of Ethiopia, Anschluss, the Munich Agreement, Spanish Civil War, and the Nazi–Soviet Non-Aggression Pact. Those developments connect directly to AP Unit 8 Learning Objective J: explain how these factors caused the catastrophe of WWII. On the exam, you’ll need to contextualize, show causation, and use evidence (DBQ/LEQ/SAQ skills). For a focused review, see the Topic 8.7 study guide (https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI) and the Unit 8 overview (https://library.fiveable.me/ap-european-history/unit-8). Practice over 1,000 questions at (https://library.fiveable.me/practice/ap-european-history).
What happened during the interwar period in Europe?
Between WWI and WWII Europe was unstable politically, economically, and ideologically—conditions that helped make WWII possible. Democracies (especially Britain and France) feared another war and practiced appeasement (e.g., Munich Agreement), U.S. isolationism reduced pressure on aggressors, and the League of Nations failed to check expansion. Economic collapse from the Great Depression fueled extremist movements: fascist regimes in Italy and Germany promoted aggressive nationalism, racism (Lebensraum), and rearmament—actions like the remilitarization of the Rhineland and Anschluss tested Western resolve. Italy’s invasion of Ethiopia and intervention in the Spanish Civil War showed international enforcement gaps. Finally, short-term deals like the Nazi–Soviet Non-Aggression Pact cleared the way for German expansion and the outbreak of WWII. For AP prep, be ready to use these examples for causation and contextualization on DBQs/LEQs and short answers (see Topic 8.7 study guide on Fiveable: https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI). For practice problems, try Fiveable’s question bank (https://library.fiveable.me/practice/ap-european-history).
Why were France and Britain so afraid of another war after WWI?
France and Britain feared another war after WWI for several linked reasons. The human and economic cost of 1914–18 was catastrophic (millions dead, shattered economies), so political leaders and publics strongly preferred peace. Both countries saw the Versailles settlement as imperfect—France worried about future German rearmament and wanted security, while Britain was exhausted and reluctant to commit to costly enforcement. That fear, combined with American isolationism, weariness of mobilization, and deep distrust of authoritarian or revolutionary states, encouraged policies of appeasement (e.g., Chamberlain’s concessions) and made Britain and France slow to check fascist aggression like the Rhineland remilitarization and Anschluss. Those choices—rooted in trauma, financial limits, and public opinion—help explain how fascist states could rearm and expand (see KC-4.1.III.A). For a clear review of this Topic 8.7, check the Fiveable study guide (https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI) and practice questions (https://library.fiveable.me/practice/ap-european-history).
How did American isolationism help fascist states expand?
American isolationism after WWI—public and Congress pushed neutrality, restrictive Neutrality Acts, and refusal to join the League—removed a major deterrent to aggression. Without the U.S. as a political, economic, or military backstop, Britain and France were more willing to pursue appeasement (Munich, Rhineland) because they feared another war and lacked sure U.S. backing. Isolationism also weakened collective responses: sanctions and collective security (e.g., weak League reaction to the Second Italo-Ethiopian War) were ineffective when the U.S. stayed out. That gave fascist regimes room to rearm (Rhineland remilitarization, Anschluss) and pursue expansionist goals like Lebensraum. For AP work, use this as a causation point in DBQs/LEQs: link U.S. neutrality to European appeasement and League failure to explain how ideological and diplomatic factors led to WWII. For a focused review, see the Topic 8.7 study guide (https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI); more unit review (https://library.fiveable.me/ap-european-history/unit-8) and 1,000+ practice questions (https://library.fiveable.me/practice/ap-european-history).
Why didn't Western democracies stop Hitler earlier when he was clearly breaking treaties?
Short answer: Western democracies didn’t stop Hitler earlier because of a mix of fear, politics, and limits. After World War I voters and leaders in Britain and France were terrified of another huge war, so they favored appeasement—giving concessions to avoid conflict (e.g., allowing the Rhineland remilitarization, Anschluss, and Munich). Economic strain from the Great Depression and American isolationism reduced willingness and resources to confront aggression. Democracies also distrusted the Soviet Union and sometimes saw Germany as a bulwark against communism, so they hesitated. The League of Nations proved ineffective at enforcing treaties (e.g., Italy in Ethiopia), and leaders like Neville Chamberlain hoped diplomacy could contain Hitler until it was too late. For AP review, connect these causes to KC-4.1.III and practice explanatory short answers in the Unit 8 study guide (https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI) and try practice questions (https://library.fiveable.me/practice/ap-european-history).
What's the difference between fascism and communism during the interwar period?
Short version: both were authoritarian and rejected liberal democracy, but they differ in goals and roots. Fascism (Mussolini, Hitler) was ultra-nationalist, often racist (Lebensraum), celebrated the nation/leader, allowed private property under strict state control, crushed leftists, and used militarism and expansion to restore national pride—helped by Western appeasement. Communism (Soviet Union under Stalin) claimed to promote international class revolution, abolished private ownership of major industry/land, aimed for a classless society, and used a one-party, planned economy with state terror to enforce policies. Practically, fascists courted traditional elites and mass nationalism; Soviet communists mobilized peasants/workers and promoted state-led modernization. Both repressed dissent and helped make WWII possible (rearmament, expansion, and distrust among democracies and USSR). For more AP-aligned review, see the Topic 8.7 study guide (https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI) and practice questions (https://library.fiveable.me/practice/ap-european-history).
Can someone explain the Munich Agreement and why it failed so badly?
The Munich Agreement (Sept. 1938) was Britain and France’s deal with Hitler letting Germany annex the Sudetenland (part of Czechoslovakia) after Nazi claims of ethnic Germans’ rights. Neville Chamberlain celebrated it as “peace for our time.” It failed because it was classic appeasement: Western democracies—scarred by WWI and facing domestic unrest—prioritized avoiding war over confronting fascist expansion. Key reasons for failure: it ignored Czech security and sovereignty, assumed Hitler’s demands would stop (they didn’t—Lebensraum and further territorial aims followed), and it signaled weakness, encouraging further aggression (Anschluss already showed earlier expansion). Within AP Euro, Munich is an illustrative example of KC-4.1.III.A and KC-4.1.III: appeasement allowing fascist rearmament and expansion, leading to WWII. Use this example in DBQs/LEQs when explaining causes of WWII (appeasement, extreme nationalism, and failed collective security). For review, see the Topic 8.7 study guide (https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI) and practice questions (https://library.fiveable.me/practice/ap-european-history).
What was the remilitarization of the Rhineland and why didn't anyone stop it?
The remilitarization of the Rhineland (March 1936) was when Hitler ordered German troops back into the demilitarized zone along the Rhine—breaking the Treaty of Versailles and the Locarno Treaties. It was a clear test of Western resolve and an early step in Nazi expansion (an AP CED illustrative example). Nobody stopped it because of Europe’s fear of another war, weak political will, and strategic caution: France and Britain were reluctant to use force (appeasement/Neville Chamberlain), the British public and politicians prioritized avoiding conflict, the U.S. stayed isolationist, and the League of Nations was ineffective. Militarily, Germany moved with limited forces so the risk of immediate large-scale fighting seemed low; Hitler gambled that democracies wouldn’t act. That failure to check rearmament helped make later Nazi expansion possible—exactly the kind of cause-and-effect you should connect on AP essays (KC-4.1.III.A). For a focused review, see the Topic 8.7 study guide (https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI). For more practice, use Fiveable’s Unit 8 page (https://library.fiveable.me/ap-european-history/unit-8) and the 1,000+ practice questions (https://library.fiveable.me/practice/ap-european-history).
How did the Nazi-Soviet Non-Aggression Pact lead to World War II?
The Nazi-Soviet Non-Aggression Pact (Molotov–Ribbentrop, Aug 1939) directly enabled World War II by removing the threat of a two-front war for Hitler and legally clearing the way for immediate territorial expansion. Publicly it promised neutrality; secretly it carved up Eastern Europe (Poland, the Baltics, Finland), so Germany could invade Poland on Sept 1, 1939 without fear of Soviet intervention. Britain and France’s guarantees to Poland then triggered their declarations of war, turning a regional invasion into a wider conflict. For the AP exam, use this as a clear causation example: the pact shows how ideological enemies (Nazi fascism and Soviet communism) made a pragmatic deal that accelerated aggression and exposed the failure of appeasement. For more review on interwar causes and practice writing causal essays, see the Topic 8.7 study guide (https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI), the Unit 8 overview (https://library.fiveable.me/ap-european-history/unit-8), and AP practice questions (https://library.fiveable.me/practice/ap-european-history).
I'm confused about appeasement - what is it and why didn't it work?
Appeasement = the policy Britain and France used in the 1930s of making concessions to aggressive states (mainly Nazi Germany) to avoid war. Leaders like Neville Chamberlain hoped limited concessions (e.g., letting Germany reoccupy the Rhineland, Anschluss with Austria, or the Sudetenland via the Munich Agreement) would satisfy demands and buy time. Why it didn’t work: it underestimated fascist goals (Lebensraum, revision of Versailles), rewarded risky behavior, and signaled weakness—encouraging further expansion (Italy in Ethiopia, then Germany’s violation of Munich). Other causes: deep fear of another world war, economic strain from the Great Depression, British/French military unpreparedness, and American isolationism. The result: appeasement failed to stop rearmament and expansion and helped lead to World War II (see CED KC-4.1.III and examples). For AP review, study these specific examples and practice related short-answer/essay prompts at Fiveable (topic study guide: https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI; practice problems: https://library.fiveable.me/practice/ap-european-history).
What were the consequences of Italy invading Ethiopia for European politics?
Italy’s 1935–36 invasion of Ethiopia had big ripple effects for European politics. It exposed the League of Nations’ weakness (sanctions were limited and ineffective), which undermined collective security and showed that democratic powers wouldn’t stop aggressive, fascist expansion (CED: League failure, Second Italo-Ethiopian War). Britain and France’s half-hearted response pushed them toward appeasement and made Mussolini more willing to cooperate with Hitler, helping form the anti-democratic axis. The episode encouraged other revisionist leaders to test Western resolve, reinforcing the CED theme that fears of another war, isolationism, and distrust enabled fascist rearmament and expansion (KC-4.1.III.A). For AP review, connect this as an illustrative example of failed collective security and appeasement (Topic 8.7 study guide: https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI). Need more practice? Try Fiveable’s practice questions (https://library.fiveable.me/practice/ap-european-history).
How do I write a DBQ essay about the causes of World War II?
Start with a clear thesis answering “why WWII happened” (e.g., “A mix of ideological aggression (fascism, Lebensraum) and weak Western responses (appeasement, isolationism) made large-scale war likely”), then contextualize briefly (post-WWI resentment, Great Depression, League weakness). During the 15-minute reading period, pick 7 documents: plan to use at least four to support your argument and one piece of outside evidence (e.g., remilitarization of the Rhineland, Anschluss, Munich Agreement, Molotov–Ribbentrop Pact, Second Italo-Ethiopian War). For two documents, explain sourcing (author’s POV/purpose/audience). Organize body paragraphs by cause (ideological expansion, diplomatic failure, economic crisis) and weave documents + outside facts into each. End with a brief complexity point (multiple motives or chronology: religious/ideological vs. strategic motives shifting over time). Remember DBQ rules: thesis (1 pt), contextualization (1 pt), use ≥4 docs (2 pts), outside evidence (1 pt), sourcing on ≥2 docs (1 pt), complexity (1 pt). For Topic 8.7 review, see the Fiveable study guide (https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI) and try practice DBQs on the unit page (https://library.fiveable.me/ap-european-history/unit-8).
Why did the annexation of Austria happen so easily?
Because the international and internal conditions made Anschluss low-risk for Hitler. Inside Austria there was a strong pro-Nazi movement and pressure from Austrian Nazis and sympathetic conservatives, so many Austrians welcomed union or didn’t resist. Externally, Britain and France were focused on avoiding war and followed a policy of appeasement—they protested but took no military action. The United States was isolationist, and the League of Nations had already shown it couldn’t stop aggression (see KC-4.1.III.A). Hitler also used propaganda about shared German identity and "Lebensraum" to justify it, and he timed the move so the German military and political pressure looked inevitable but not immediately dangerous for other powers. For AP exam purposes, link this to learning objective J: show how appeasement, extreme nationalism, and weak collective security allowed fascist expansion and led toward WWII. For a concise topic review, check the Topic 8.7 study guide (https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI) and try practice questions (https://library.fiveable.me/practice/ap-european-history).
I don't understand how distrust between democracies and the Soviet Union helped fascists - can someone break this down?
Think of it like three sets of enemies who mistrusted each other and didn’t cooperate—that opened space for fascists. After WWI Western democracies (Britain, France, U.S. isolationism) feared another war and also feared communism. They distrusted the USSR and were reluctant to form a broad anti-fascist alliance with Stalin. Meanwhile conservative elites sometimes saw Hitler and Mussolini as a bulwark against Bolshevism and tolerated or appeased them (Rhineland, Anschluss, Munich). That lack of coordinated opposition let fascist states rearm and expand without facing a united front; Hitler even exploited Western fears to demand concessions. The Nazi–Soviet Non-Aggression Pact later showed how mutual distrust pushed rivals into short-term deals instead of collective security. For AP review, this connects directly to KC-4.1.III.A—see the Topic 8.7 study guide for concise examples and practice (https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI). For extra practice, check Fiveable’s Unit 8 resources (https://library.fiveable.me/ap-european-history/unit-8) and the practice question bank (https://library.fiveable.me/practice/ap-european-history).
What were the long-term effects of European powers allowing fascist expansion?
Allowing fascist expansion had huge long-term consequences: it rewarded aggression, eroded collective security, and made World War II more likely. Appeasement (e.g., Chamberlain at Munich), U.S. isolationism, and distrust of the USSR let Germany rearm and take the Rhineland, annex Austria (Anschluss), and violate Munich without serious pushback. Italy’s invasion of Ethiopia and the League of Nations’ failure signaled that international norms weren’t enforced. Those concessions strengthened fascist regimes, shifted the balance of power, and forced opponents into risky responses (including the Nazi–Soviet pact). For the AP exam, connect these causes to KC-4.1.III and use posters like the Spanish Civil War as evidence in short answers/DBQs to show how ideological divides and appeasement produced the “catastrophe” of WWII. Want a focused Topic 8.7 review? Check Fiveable’s study guide (https://library.fiveable.me/ap-european-history/unit-8/europe-during-interwar-period/study-guide/dKUCP8hISShrFrl8cDTI) and try over 1,000 practice questions (https://library.fiveable.me/practice/ap-european-history) to practice causation and contextualization.